1. Field
The described technology relates generally to a flexible display device, and to a flexible display device that can reduce durability deterioration even in the case of continuous or repeated folding.
2. Description of the Related Art
Various display devices that include a flat panel display, such as a liquid crystal display, an electric field emission display, a plasma display panel, an organic light emitting display, and the like, have been developed.
With the recent development of display-related techniques, deformable display devices, which are, for example, foldable, rollable, or stretchable like a rubber band, have been researched and developed. The display devices may display various user interfaces and images depending on a deformation form, and thus utilization thereof is high.
Among them, in a foldable display device, which is folded based on one axis, to satisfy foldable flexibility, respective layers, such as a cover window, a touch substrate, and a display substrate, are formed as thin as possible, and adhesive layers are formed using a high elastic material, such as an optical clear resin (OCR) or a pressure sensitive adhesive (PSA) to adhere the respective layers.
However, when the foldable display device is continuously or repeatedly folded, the adhesive layer positioned in the folding axis exhibits elastic deformation as compared to the peripheral areas, and non-uniform stress distribution is repeated at the same adhesive layer, thereby generating plastic deformation of the adhesive layer. This causes delamination between the adhesive layer and other layers. Thus, the overall durability of the flexible display device is deteriorated.
The above information disclosed in this Background section is only to enhance the understanding of the background of the invention, and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.